Coordination Compounds

2023 Q151 JEE Mains MCQ
14 Mar 2026

A solution of $\mathrm{FeCl_3}$ when treated with $\mathrm{K_4[Fe(CN)_6]}$ gives a prussium blue precipitate due to the formation of :

A.
$\mathrm{Fe[Fe(CN)_{6}]}$
B.
$\mathrm{Fe_{4}[Fe(CN)_{6}]_{3}}$
C.
$\mathrm{Fe_{3}[Fe(CN)_{6}]_{2}}$
D.
$\mathrm{K[Fe_{2}(CN)_{6}]}$
2023 Q152 JEE Mains MCQ
14 Mar 2026

Cobalt chloride when dissolved in water forms pink colored complex $\underline{\mathrm{X}}$ which has octahedral geometry. This solution on treating with conc $\mathrm{HCl}$ forms deep blue complex, $\underline{\mathrm{Y}}$ which has a $\underline{\mathrm{Z}}$ geometry. $\mathrm{X}, \mathrm{Y}$ and $\mathrm{Z}$, respectively, are

A.
$\mathrm{X}=\left[\mathrm{Co}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{2+}, \mathrm{Y}=\left[\mathrm{CoCl}_{4}\right]^{2-}, \mathrm{Z}=$ Tetrahedral
B.
$\mathrm{X}=\left[\mathrm{Co}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{2+}, \mathrm{Y}=\left[\mathrm{CoCl}_{6}\right]^{3-}, \mathrm{Z}=$ Octahedral
C.
$\mathrm{X}=\left[\mathrm{Co}\left(\mathrm{H}_{2} \mathrm{O}\right)_{4} \mathrm{Cl}_{2}\right]^{+}, \mathrm{Y}=\left[\mathrm{CoCl}_{4}\right]^{2-}, \mathrm{Z}=$ Tetrahedral
D.
$\mathrm{X}=\left[\mathrm{Co}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{3+}, \mathrm{Y}=\left[\mathrm{CoCl}_{6}\right]^{3-}, \mathrm{Z}=$ Octahedral
2023 Q153 JEE Mains MCQ
14 Mar 2026

Match List I with List II:

List I (Complexes) List II (Hybridisation)
A. $\left[\mathrm{Ni}(\mathrm{CO})_{4}\right]$ I. $\mathrm{sp}^{3}$
B. $\left[\mathrm{Cu}\left(\mathrm{NH}_{3}\right)_{4}\right]^{2+}$ II. dsp$^{2}$
C. $\left[\mathrm{Fe}\left(\mathrm{NH}_{3}\right)_{6}\right]^{2+}$ III. $\mathrm{sp}^{3}\mathrm{d}^{2}$
D. $\left[\mathrm{Fe}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{2+}$ IV. $\mathrm{d}^{2} \mathrm{sp}^{3}$
A.
A-I, B-II, C-III, D-IV
B.
A-II, B-I, C-III, D-IV
C.
A-I, B-II, C-IV, D-III
D.
A-II, B-I, C-IV, D-III
2023 Q154 JEE Mains MCQ
14 Mar 2026
The $\mathrm{Cl}-\mathrm{Co}-\mathrm{Cl}$ bond angle values in a fac- $\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{3} \mathrm{Cl}_{3}\right]$ complex is/are :
A.
$90^{\circ} ~\&~ 120^{\circ}$
B.
$90^{\circ}$
C.
$180^{\circ}$
D.
$90^{\circ} ~\& ~180^{\circ}$
2023 Q155 JEE Mains MCQ
14 Mar 2026

To inhibit the growth of tumours, identify the compounds used from the following :

A. EDTA

B. Coordination Compounds of Pt

C. D - Penicillamine

D. Cis - Platin

Choose the correct answer from the option given below :

A.
A and B Only
B.
C and D Only
C.
B and D Only
D.
A and C Only
2023 Q156 JEE Mains MCQ
14 Mar 2026

Which of the following is correct order of ligand field strength?

A.
$\mathrm{S}^{2-}<\mathrm{C}_{2} \mathrm{O}_{4}^{2-}<\mathrm{NH}_{3} < $ en $<\mathrm{CO}$
B.
$\mathrm{CO}<\mathrm{en}<\mathrm{NH}_{3}<\mathrm{C}_{2} \mathrm{O}_{4}^{2}<\mathrm{S}^{2-}$
C.
$\mathrm{S}^{2-}<\mathrm{NH}_{3}<$ en $<\mathrm{CO}<\mathrm{C}_{2} \mathrm{O}_{4}^{2}$
D.
$\mathrm{NH}_{3}<\mathrm{en}<\mathrm{CO}<\mathrm{S}^{2-}<\mathrm{C}_{2} \mathrm{O}_{4}^{2}$
2023 Q157 JEE Mains MCQ
14 Mar 2026

Correct order of spin only magnetic moment of the following complex ions is :

(Given At.no. Fe : 26, Co : 27)

A.
$\mathrm{[CoF_6]^{3-} > [FeF_6]^{3-} > [Co(C_2O_4)_3]^{3-}}$
B.
$\mathrm{[FeF_6]^{3-} > [Co(C_2O_4)_3]^{3-} > [CoF_6]^{3-}}$
C.
$\mathrm{[FeF_6]^{3-} > [CoF_6]^{3-} > [Co(C_2O_4)_3]^{3-}}$
D.
$\mathrm{[Co(C_2O_4)_3]^{3-} > [CoF_6]^{3-} > [FeF_6]^{3-}}$
2023 Q158 JEE Mains MCQ
14 Mar 2026

Chiral complex from the following is :

Here en = ethylene diamine

A.
$\mathrm{cis-[PtCl_2(en)_2]^{2+}}$
B.
$\mathrm{trans-[Co(NH_3)_4Cl_2]^{+}}$
C.
$\mathrm{trans-[PtCl_2(en)_2]^{2+}}$
D.
$\mathrm{cis-[PtCl_2(NH_3)_2]}$
2023 Q159 JEE Mains MCQ
14 Mar 2026

Match List I with List II

List I
Coordination entity
List II
Wavelength of light absorbed in nm
A. $\mathrm{[CoCl(NH_3)_5]^{2+}}$ I. 310
B. $\mathrm{[Co(NH_3)_6]^{3+}}$ II. 475
C. $\mathrm{[Co(CN)_6]^{3-}}$ III. 535
D. $\mathrm{[Cu(H_2O)_4]^{2+}}$ IV. 600

Choose the correct answer from the options given below :

A.
A-IV, B-I, C-III, D-II
B.
A-III, B-II, C-I, D-IV
C.
A-III, B-I, C-II, D-IV
D.
A-II, B-III, C-IV, D-I
2023 Q160 JEE Mains MCQ
14 Mar 2026

The hybridization and magnetic behaviour of cobalt ion in $\mathrm{[Co(NH_3)_6]^{3+}}$ complex, respectively is :

A.
$\mathrm{sp^3d^2}$ and paramagnetic
B.
$\mathrm{sp^3d^2}$ and diamagnetic
C.
$\mathrm{d^2sp^3}$ and diamagnetic
D.
$\mathrm{d^2sp^3}$ and paramagnetic
2023 Q161 JEE Mains MCQ
14 Mar 2026

Which of the following cannot be explained by crystal field theory?

A.
The order of spectrochemical series
B.
Stability of metal complexes
C.
Magnetic properties of transition metal complexes
D.
Colour of metal complexes
2023 Q162 JEE Mains MCQ
14 Mar 2026

The primary and secondary valencies of cobalt respectively in $\mathrm{[Co(NH_3)_5Cl]Cl_2}$ are :

A.
2 and 8
B.
2 and 6
C.
3 and 5
D.
3 and 6
2023 Q163 JEE Mains Numerical
14 Mar 2026
The homoleptic and octahedral complex of $\mathrm{Co}^{2+}$ and $\mathrm{H}_{2} \mathrm{O}$ has ___________ unpaired electron(s) in the $t_{2\mathrm{g}}$ set of orbitals.
2023 Q164 JEE Mains Numerical
14 Mar 2026

The ratio of spin-only magnetic moment values $\mu_{\text {eff }}\left[\mathrm{Cr}(\mathrm{CN})_{6}\right]^{3-} / \mu_{\text {eff }}\left[\mathrm{Cr}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{3+}$ is _________.

2023 Q165 JEE Mains Numerical
14 Mar 2026

For a metal ion, the calculated magnetic moment is $4.90 ~\mathrm{BM}$. This metal ion has ___________ number of unpaired electrons.

2023 Q166 JEE Mains Numerical
14 Mar 2026

In potassium ferrocyanide, there are ________ pairs of electrons in the $t_{2g}$ set of orbitals.

2023 Q167 JEE Mains Numerical
14 Mar 2026

The observed magnetic moment of the complex $\left.\left[\operatorname{Mn}(\underline{N} C S)_{6}\right)\right]^{x^{-}}$ is $6.06 ~\mathrm{BM}$. The numerical value of $x$ is __________.

2023 Q168 JEE Mains Numerical
14 Mar 2026

Number of ambidentate ligands in a representative metal complex $\left[\mathrm{M}(\mathrm{en})(\mathrm{SCN})_{4}\right]$ is ___________.

[en = ethylenediamine]

2023 Q169 JEE Mains Numerical
14 Mar 2026

The spin only magnetic moment of $\left[\mathrm{Mn}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{2+}$ complexes is _________ B.M. (Nearest integer)

(Given : Atomic no. of Mn is 25)

2023 Q170 JEE Mains Numerical
14 Mar 2026
If the CFSE of $\left[\mathrm{Ti}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{3+}$ is $-96.0 \mathrm{~kJ} / \mathrm{mol}$, this complex will absorb maximum at wavelength ___________ $\mathrm{nm}$. (nearest integer)

Assume Planck's constant (h) $=6.4 \times 10^{-34} \mathrm{Js}$, Speed of light $(\mathrm{c})=3.0 \times 10^{8} \mathrm{~m} / \mathrm{s}$ and Avogadro's

Constant $\left(\mathrm{N}_{\mathrm{A}}\right)=6 \times 10^{23} / \mathrm{mol}$
2023 Q171 JEE Mains Numerical
14 Mar 2026

The sum of bridging carbonyls in $\mathrm{W(CO)_6}$ and $\mathrm{Mn_2(CO)_{10}}$ is ____________.

2023 Q172 JEE Mains Numerical
14 Mar 2026

Total number of moles of AgCl precipitated on addition of excess of AgNO$_3$ to one mole each of the following complexes $\mathrm{[Co(NH_3)_4Cl_2]Cl,[Ni(H_2O)_6]Cl_2,[Pt(NH_3)_2Cl_2]}$ and $\mathrm{[Pd(NH_3)_4]Cl_2}$ is ___________.

2023 Q173 JEE Mains Numerical
14 Mar 2026

The number of paramagnetic species from the following is _____________.

$\mathrm{{[Ni{(CN)_4}]^{2 - }},[Ni{(CO)_4}],{[NiC{l_4}]^{2 - }}}$

$\mathrm{{[Fe{(CN)_6}]^{4 - }},{[Cu{(N{H_3})_4}]^{2 + }}}$

$\mathrm{{[Fe{(CN)_6}]^{3 - }}\,and\,{[Fe{({H_2}O)_6}]^{2 + }}}$

2023 Q174 JEE Mains Numerical
14 Mar 2026

The d-electronic configuration of $\mathrm{[CoCl_4]^{2-}}$ in tetrahedral crystal field in ${e^mt_2^n}$. Sum of "m" and "number of unpaired electrons" is ___________

2022 Q175 JEE Mains MCQ
14 Mar 2026

Octahedral complexes of copper(II) undergo structural distortion (Jahn-Teller). Which one of the given copper (II) complexes will show the maximum structural distortion? (en - ethylenediamine; $\mathrm{H}_{2} \mathrm{~N}_{-} \mathrm{CH}_{2}-\mathrm{CH}_{2}-\mathrm{NH}_{2}$)

A.
$\left[\mathrm{Cu}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right] \mathrm{SO}_{4}$
B.
$\left[\mathrm{Cu}(\mathrm{en})\left(\mathrm{H}_{2} \mathrm{O}\right)_{4}\right] \mathrm{SO}_{4}$
C.
cis-$\left[\mathrm{Cu}\left(\mathrm{en})_{2} \mathrm{Cl}_{2}\right]\right.$
D.
trans-$\left[\mathrm{Cu}\left(\mathrm{en})_{2} \mathrm{Cl}_{2}\right]\right.$
2022 Q176 JEE Mains MCQ
14 Mar 2026

Match List I with List II

List - I (Complex) List - II (Hybridization)
(A) $Ni{(CO)_4}$ (I) $s{p^3}$
(B) ${[Ni{(CN)_4}]^{2 - }}$ (II) $s{p^3}{d^2}$
(C) ${[Co{(CN)_6}]^{3 - }}$ (III) ${d^2}s{p^3}$
(D) ${[Co{F_6}]^{3 - }}$ (IV) $ds{p^2}$

Choose the correct answer from the options given below :

A.
A-IV, B-I, C-III, D-II
B.
A-I, B-IV, C-III, D-II
C.
A-I, B-IV, C-II, D-III
D.
A-IV, B-I, C-II, D-III
2022 Q177 JEE Mains MCQ
14 Mar 2026

Low oxidation state of metals in their complexes are common when ligands :

A.
have good $\pi$-accepting character
B.
have good $\sigma$-donor character
C.
are having good $\pi$-donating ability
D.
are having poor $\sigma$-donating ability
2022 Q178 JEE Mains MCQ
14 Mar 2026

$\mathrm{Fe}^{3+}$ cation gives a prussian blue precipitate on addition of potassium ferrocyanide solution due to the formation of :

A.
$\left[\mathrm{Fe}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]_{2}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]$
B.
$\mathrm{Fe}_{2}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]_{2}$
C.
$\mathrm{Fe}_{3}\left[\mathrm{Fe}(\mathrm{OH})_{2}(\mathrm{CN})_{4}\right]_{2}$
D.
$\mathrm{Fe}_{4}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]_{3}$
2022 Q179 JEE Mains MCQ
14 Mar 2026

The metal complex that is diamagnetic is (Atomic number: $\mathrm{Fe}, 26 ; \mathrm{Cu}, 29)$

A.
$\mathrm{K}_{3}\left[\mathrm{Cu}(\mathrm{CN})_{4}\right]$
B.
$\mathrm{K}_{2}\left[\mathrm{Cu}(\mathrm{CN})_{4}\right]$
C.
$\mathrm{K}_{3}\left[\mathrm{Fe}(\mathrm{CN})_{4}\right]$
D.
$\mathrm{K}_{4}\left[\mathrm{FeCl}_{6}\right]$
2022 Q180 JEE Mains MCQ
14 Mar 2026

The correct order of energy of absorption for the following metal complexes is :

A : [Ni(en)3]2+ , B : [Ni(NH3)6]2+ , C : [Ni(H2O)6]2+

A.
C < B < A
B.
B < C < A
C.
C < A < B
D.
A < C < B
2022 Q181 JEE Mains MCQ
14 Mar 2026

Correct formula of the compound which gives a white precipitate with BaCl2 solution, but not with AgNO3 solution, is :

A.
[Co(NH3)5Br]SO4
B.
[Co(NH3)5SO4]Br
C.
[Pt(NH3)4Cl2]Br2
D.
[Pt(NH3)4Br2]Cl2
2022 Q182 JEE Mains MCQ
14 Mar 2026

Given below are two statements.

$\bullet$ Statement I : In CuSO4 . 5H2O, Cu-O bonds are present.

$\bullet$ Statement II : In CuSO4 . 5H2O, ligands coordinating with Cu(II) ion are O-and S-based ligands.

In the light of the above statements, choose the correct answer from the options given below.

A.
Both Statement I and Statement II are correct.
B.
Both Statement I and Statement II are incorrect.
C.
Statement I is correct but Statement II is incorrect.
D.
Statement I is incorrect but Statement II is correct.
2022 Q183 JEE Mains MCQ
14 Mar 2026

Given below are two statements :

Statement I : [Ni(CN)4]2$-$ is square planar and diamagnetic complex, with dsp2 hybridization for Ni but [Ni(CO)4] is tetrahedral, paramagnetic and with sp3-hybridication for Ni.

Statement II : [NiCl4]2$-$ and [Ni(CO)4] both have same d-electron configuration have same geometry and are paramagnetic.

In light the above statements, choose the correct answer from the options given below :

A.
Both Statement I and Statement II are true.
B.
Both Statement I and Statement II are false.
C.
Statement I is correct but Statement II is false.
D.
Statement I is false but Statement II is correct.
2022 Q184 JEE Mains MCQ
14 Mar 2026

Arrange the following coordination compounds in the increasing order of magnetic moments. (Atomic numbers : Mn = 25; Fe = 26)

A. [FeF6]3$-$

B. [Fe(CN)6]3$-$

C. [MnCl6]3$-$ (high spin)

D. [Mn(CN)6]3$-$

Choose the correct answer from the options given below :

A.
A < B < D < C
B.
B < D < C < A
C.
A < C < D < B
D.
B < D < A < C
2022 Q185 JEE Mains MCQ
14 Mar 2026

Which of the following will have maximum stabilization due to crystal field?

A.
[Ti(H2O)6]3+
B.
[Co(H2O)6]2+
C.
[Co(CN)6]3$-$
D.
[Cu(NH3)4]2+
2022 Q186 JEE Mains MCQ
14 Mar 2026

Which statement is not true with respect to nitrate ion test?

A.
A dark brown ring is formed at the junction of two solutions.
B.
Ring is formed due to nitroferrous sulphate complex.
C.
The brown complex is [Fe(H2O)5 (NO)]SO4.
D.
Heating the nitrate salt with conc. H2SO4, light brown fumes are evolved.
2022 Q187 JEE Mains MCQ
14 Mar 2026

Transition metal complex with highest value of crystal field splitting ($\Delta$0) will be :

A.
[Cr(H2O)6]3+
B.
[Mo(H2O)6]3+
C.
[Fe(H2O)6]3+
D.
[Os(H2O)6]3+
2022 Q188 JEE Mains MCQ
14 Mar 2026

Match List - I with List - II :

List - I List -II
(A) ${[PtC{l_4}]^{2 - }}$ (I) $s{p^3}d$
(B) $Br{F_5}$ (II) ${d^2}s{p^3}$
(C) $PC{l_5}$ (III) $ds{p^2}$
(D) ${[Co{(N{H_3})_6}]^{3 + }}$ (IV) $s{p^3}{d^2}$

Choose the most appropriate answer from the options given below :

A.
(A)-(II), (B)-(IV), (C)-(I), (D)-(III)
B.
(A)-(III), (B)-(IV), (C)-(I), (D)-(II)
C.
(A)-(III), (B)-(I), (C)-(IV), (D)-(II)
D.
(A)-(II), (B)-(I), (C)-(IV), (D)-(III)
2022 Q189 JEE Mains Numerical
14 Mar 2026

Sum of oxidation state (magnitude) and coordination number of cobalt in $\mathrm{Na}\left[\mathrm{Co}(\mathrm{bpy}) \mathrm{Cl}_{4}\right]$ is _________.

JEE Main 2022 (Online) 29th July Evening Shift Chemistry - Coordination Compounds Question 175 English

2022 Q190 JEE Mains Numerical
14 Mar 2026

$\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]^{3-}$ should be an inner orbital complex. Ignoring the pairing energy, the value of crystal field stabilization energy for this complex is $(-)$ ____________ $\Delta_{0}$. (Nearest integer)

2022 Q191 JEE Mains Numerical
14 Mar 2026

Total number of relatively more stable isomer(s) possible for octahedral complex $\left[\mathrm{Cu}(\mathrm{en})_{2}(\mathrm{SCN})_{2}\right]$ will be _________.

2022 Q192 JEE Mains Numerical
14 Mar 2026

The conductivity of a solution of complex with formula $\mathrm{CoCl}_{3}\left(\mathrm{NH}_{3}\right)_{4}$ corresponds to 1 : 1 electrolyte, then the primary valency of central metal ion is __________.

2022 Q193 JEE Mains Numerical
14 Mar 2026

The difference between spin only magnetic moment values of $\left[\mathrm{Co}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]\mathrm{Cl}_{2}$ and $\left[\mathrm{Cr}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right] \mathrm{Cl}_{3}$ is ___________.

2022 Q194 JEE Mains Numerical
14 Mar 2026

Consider the following metal complexes :

$\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{6}\right]^{3+}$

$\left[\mathrm{CoCl}\left(\mathrm{NH}_{3}\right)_{5}\right]^{2+}$

$\left[\mathrm{Co}(\mathrm{CN})_{6}\right]^{3-}$

$\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{5}\left(\mathrm{H}_{2} \mathrm{O}\right)\right]^{3+}$

The spin-only magnetic moment value of the complex that absorbes light with shortest wavelength is _____________ B. M. (Nearest integer)

2022 Q195 JEE Mains Numerical
14 Mar 2026

In the following brown complex, the oxidation state of iron is +_____________.

${[Fe{({H_2}O)_6}]^{2 + }} + NO \to \mathop {{{[Fe{{({H_2}O)}_5}(NO)]}^{2 + }}}\limits_{\text{Brown complex}} + {H_2}O$

2022 Q196 JEE Mains Numerical
14 Mar 2026

Spin only magnetic moment ($\mu$s) of ${K_3}[Fe{(CN)_6}]$ is ____________ B.M.

(Nearest integer)

2022 Q197 JEE Mains Numerical
14 Mar 2026

${[Fe{(CN)_6}]^{4 - }}$

${[Fe{(CN)_6}]^{3 - }}$

${[Ti{(CN)_6}]^{3 - }}$

${[Ni{(CN)_4}]^{2 - }}$

${[Co{(CN)_6}]^{3 - }}$

Among the given complexes, number of paramagnetic complexes is ____________.

2022 Q198 JEE Mains Numerical
14 Mar 2026

(a) CoCl3.4NH3,    (b) CoCl3.5NH3,      (c) CoCl3.6NH3    and    (d) CoCl(NO3)2.5NH3.

Number of complex(es) which will exist in cis-trans form is/are _______________.

2022 Q199 JEE Mains Numerical
14 Mar 2026

Number of complexes which will exhibit synergic bonding amongst, $[Cr{(CO)_6}]$, $[Mn{(CO)_5}]$ and $[M{n_2}{(CO)_{10}}]$ is ___________.

2022 Q200 JEE Mains Numerical
14 Mar 2026

Acidified potassium permanganate solution oxidises oxalic acid. The spin-only magnetic moment of the manganese product formed from the above reaction is ____________ B.M. (Nearest integer)